The present invention relates to acoustic positioning methods, and more particularly, but not exclusively to a method and an apparatus for data entry using an acoustic signal transmitting pen input device.
Digital writing instruments, interchangeably referred to herein as Digital Pens, regardless of whether they actually write on paper, can be used to capture pen strokes on paper and digitize them.
For example, with a digital pen, pen strokes may be converted by handwriting recognition software to a digitally stored record of the writing. In this way, a laborious, tedious step in modern written communication, namely, the manual transcribing of handwriting into a computerized word processor, is eliminated, greatly increasing productivity.
Sensing a time-dependent position of the pen and converting the positions to pen strokes may be used for input of digital representations of the pen strokes to a handwriting recognition device.
As known in the art, ultrasonic systems can be used in which a special pen generates or alters an ultrasonic signal, as the pen is moved across a piece of paper.
The ultrasonic signal is sensed by receivers and correlated to a position vis-à-vis each receiver, as the outputs of the receivers is triangulated and correlated to absolute pen positions. A sequence of pen positions can then be digitized for input into handwriting recognition engines.
An advantage with ultrasonic systems is that the user of the ultrasonic signal emitting device can use the device to write on an ordinary piece of paper that is placed on or nearby a base station, which receives the ultrasonic signals and converts the signals to alpha-numeric characters.
There are many currently known in the art methods for data entry using an acoustic impulse transmitting pen input device.
U.S. Pat. No. 4,814,552, to Stefik, filed on Dec. 2, 1987, entitled “Ultrasonic position input device”, describes an input device, or stylus, for entering hand drawn forms into a computer comprising a writing instrument, a pressure switch for determining whether the instrument is in contact with the writing surface, an acoustic transmitter for triangulating the position of the stylus on the surface, and a wireless transmitter for transmitting data and timing information to the computer.
In operation, the stylus described by Stefik transmits an infrared signal which the system receives immediately, and an ultrasound pulse which two microphones receive after a delay which is a function of the speed of sound and the distance of the stylus from each microphone.
U.S. Pat. No. 6,654,008, to Ikeda, filed on Nov. 27, 2001, entitled “Electronic whiteboard and penholder used for the same”, describes an electronic whiteboard capable of being drawn, using marker pens of several colors, and one penholder for use in such an electronic whiteboard.
In Ikeda's patent, an infrared light emitting unit emits infrared light containing color information of the marker pen, an ultrasonic wave emitting unit emits the ultrasonic wave, and color information changeover means changes over color information depending on the color of marker pen. The electronic whiteboard main body receives the infrared light and ultrasonic wave emitted from the penholder, and issues information about a position of the penholder depending on the reception timing of the infrared light and ultrasonic wave.
U.S. Pat. No. 6,876,356 to Zloter, filed on Mar. 18, 2002, entitled “Digitizer pen”, describes a digitizer pen system including a pen having a means protruding from the pen's writing tip, for preventing fingers blocking communication with a base unit.
U.S. Pat. No. 6,184,873 to Ward, filed on Jan. 20, 1998, entitled “Pen positioning system”, describes a pen positioning system including a pen. The pen has multiple output elements and is adapted to accurately determine the location of the pointing tip of the pen, in relation to an electronic tablet.
The output elements, preferably ultrasonic transmitters having distinct frequencies, are located a fixed distance from each other, and are also related in space to the pointing tip of the pen.
A detection system is used to receive the output signals from the output elements, isolate the output signals from each other, and process them independently, to determine the location of the output elements and of the pointing tip of the pen.
U.S. Pat. No. 6,703,570 to Russel, filed on May 10, 2000, entitled “Digital pen using ultrasonic tracking”, describes a digital pen system. Russel's system includes an elongated pen defining a writing tip, and an ultrasonic transducer oriented on the pen to direct frames of ultrasonic energy outwardly from the pen, with each frame including plural receive pulses.
The digital pen system in Russel's patent further includes two or more detectors positioned on a base, such as a laptop computer, for receiving the pulses, with each pulse being associated with at least one pulse time of arrival (TOA) relative to at least one detector. Russel's system further includes a processor positioned on the base, receiving signals from the detectors, and outputting position signals representative of positions of the pen, based on the received signals.
However, there are inherent problems in current acoustical technology and in the implementation of the current acoustical technology in digital pens, such as the digital pens described in the patents cited hereinabove.
Among the disadvantages of current acoustic technology are: lack of accuracy, lack of multi-devices support, high power consumption, etc. The problems have implications on the mechanical design of existing data entry using an acoustic impulse transmitting devices.
Apart from that, there are manufacturing problems related to the assembly of the acoustic transmitter and its incorporation in a digital pen or the like. For instance, such problems may arise in connecting an acoustic transmitter to a flexible printed circuit board (PCB). There are also marketing issues, such as differentiation between products by changing their appearance, while keeping the functional parts the same.
There is thus a widely recognized need for, and it would be highly advantageous to have, an apparatus or a method devoid of the above limitations.